State one prediction of Maxwell’s theory of electromagnetism that is consistent with special relativity.

A current is established in a long straight wire that is at rest in a laboratory.

A proton is at rest relative to the laboratory and the wire.

Observer X is at rest in the laboratory. Observer Y moves to the right with constant speed relative to the laboratory. Compare and contrast how observer X and observer Y account for any non-gravitational forces on the proton.

the speed of light is a universal constant/invariant
OR
c does not depend on velocity of source/observer

electric and magnetic fields/forces unified/frame of reference dependant

[1 mark]

observer X will measure zero «magnetic or electric» force

observer Y must measure both electric and magnetic forces

which must be equal and opposite so that observer Y also measures zero force

Allow [2 max] for a comment that both X and Y measure zero resultant force even if no valid explanation is given.

[3 marks]